OK. If it's not VDEV_SUPPORT, than it's elsewhere... We can either go back in hg and see which revision is fine (Does r445 crash?), or try the debug symbols again.

I'm sorry, but the procedure to make debug versions is a bit more complicated than I though:
A. Use "CC=cc -g" configure
B. Edit Makefile.osscore and add "DEBUG_FLAGS=-g"
C. Edit Makefile.tmpl and add "DEBUG_FLAGS=-g"
D. Change install.sh to copy "*.ko*" instead of "*.ko", and make sure the previous .ko files don't exist/are erased (the suffix will be .ko.debug now).
E. Now kgdb should work (thotypous managed to do it this way).

~# kgdb /boot/kernel/kernel /var/crash/vmcore.0 GNU gdb 6.1.1 [FreeBSD]Copyright 2004 Free Software Foundation, Inc.GDB is free software, covered by the GNU General Public License, and you arewelcome to change it and/or distribute copies of it under certain conditions.Type "show copying" to see the conditions.There is absolutely no warranty for GDB. Type "show warranty" for details.This GDB was configured as "amd64-marcel-freebsd"...

I haven't seen you on IRC lately, but I wanted to let you know that the patch you gave me on Friday seems to be working great. I haven't had a single kernel panic or application lockup since I rebuilt OSS with the patch.

At the moment i don't have any FreeBSD machine, i remember i had this problem some months ago with version 7.2...Now i'm planning to switch back my laptop to FreeBSD when version 8.0 will be released and this bug was crucial for me.FreeBSD ports systems now supports OSS build 2000 so this bug should be fixed. Thank you very much!

Oh, you're building this manually... See this page for how to build OSS. The build system uses a separate build directory (the build directory will be the directory configure is run from). So do something like "mkdir build", "cd build", "../configure", etc.

finally i installed the modified oss b2002 (with USE_SX_LOCK enabled) on my FreeBSD 8.0 laptop.I tried to play a video with mplayer but unfortunately it freezes after some minutes... according to top it is blocked with "STATE=oss".It is a very annoying problem...